1. Technical Field
The present invention relates to a thin film common mode filter and a method of manufacturing the same, and a thin film common mode filter including an insulating layer made of a composite of ferrite powder and thermosetting resin and a method of manufacturing the same.
2. Description of the Related Art
As a technology development speed is accelerated, a resolution of electronic devices, such as a mobile phone, a digital TV, and the like, is gradually increased and a data amount transmitted between the electronic devices or within the electronic devices is gradually increased, such that a fast transmission environment, such as HDMI, DVI, MHL, USB 2.0, USB 3.0, and the like, is required.
These interfaces have adopted a differential signal system that uses a pair of signal lines to transmit differential signals (differential mode signals), unlike a single-end transmission system that has been generally used for a long time. However, high-speed digitalized electronic devices are sensitive to a stimulus from the outside.
That is, when small abnormal voltage and high frequency noise are introduced into an internal circuit of the electronic device from the outside, a circuit may be damaged or a signal may be distorted.
In order to prevent the circuit damage of the electronic device or the signal distortion from occurring, a filter is mounted to prevent the abnormal voltage and the high frequency noise from being introduced into the circuit. In general, a common mode filter has been used in a fast differential signal line, and the like, to remove a common mode noise.
The common mode noise is a noise occurring in the differential signal line and the common mode filter removes noise that may not be removed by the existing EMI filter. The common mode filter contributes to the improvement of EMC characteristics, such as home appliances, and the like or improvement in antenna characteristics, such as a mobile phone, and the like.
As a frequency of a signal between home appliances is increased, the use of a filter for removing the common mode noise has been inevitably increased.
Further, as a demand for the small and multi-functional electronic devices is increased, the common mode filter also uses a thin film technology to implement high impedance at the same size.
In general, the common mode filter has a structure in which a primary metal internal coil and a secondary metal internal coil that are enclosed with an insulating resin material are each formed on a body substrate, that is a ferrite sintered body, in a spiral shape and both ends of each coil are connected with external electrode terminals.
In this case, the primary and secondary internal coils are each inter-layer-insulated with the same or similar as or to the insulating resin material to prevent a magnetic flux from being leaked to a side of the common mode filter and concentrate a magnetic flux on a core of the common mode filter.
In the related art, an insulating layer insulating between coil layers is formed on the ferrite substrate by using only the thermosetting resin to obtain an effect of offsetting a magnetic flux within the common mode filter. Therefore, the related art has a limitation in the increase in impedance capacity as a size of a common mode filter is reduced.